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Matt, Mechanical Engineer
Category: Ford
Satisfied Customers: 218
Experience:  BEng hons Mech engineering, in auto industry 22 years
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Hi, i am kieran, I have a customer car in for repair 2006 s

Customer Question

Hi, i am kieran, I have a customer car in for repair 2006 s Max 1.8 tdci. Problem is as follows, only when driving all gears/road & engine speeds/loads/throttle position except idle or coasting with the clutch pressed the vehicle jerks very violently & rapidly due to loss of engine power for maybe 1-2 seconds and is totally erratic & random, but the longer i drive the worse it gets. Its ok for approx first 15 mins from cold start then progressively gets worse as journey progresses until vehicle becomes undrivable. Very similar to switching ignition off/on quickly but have discounted ignition switch as electrical items that fail when problem occurs are different to ignition controlled induced problem. First thing noticeable is dip/main lights get weaker by approx 15% at the same time radio goes off/on but time clock remains correct, heated front & rear screens switch off until switched on manually from dash switches, front rear wipers stop for split second, rpm counter will fall slowly as rpm goes down and back up when power restored but not to zero, battery light will flash on until engine power restored after the 1-2 second fault, some times oil light will flash on, interior lights willl also go dimmer, other dash lights illumination will stay normal, SRS/ABS lights will remain off. DTC which keeps popping up is U0140 lost comms body control module. Have checked all the usual bad connections/earths/fuses, swapped few main relays from other vehicle etc & no fix. Live data during the fault on both PCM & BCM with my launch X431 scanner shows charging & ecu module voltages to spike downwards from approx 14.5v to approx 12v when on a graph scale during the jerking and on some occasions actually lower as my scanner actually powers off completely due to low voltage.Fuel pressure & throttle position remain good during the jerking. I am suspecting a intermittent short circuit in either alternator/battery/fuse box/ecu etc etc. I am going to try measure actual battery voltage during the fault but digital multimeter may not record it as it happens so fast. Have you ever experienced this before or any other suggestions to offer. Note the mph gauge does not alter during the fault except the normal fall off due to lost power. I have replaced the throttle pedal sensor as this showed up during the first DTC scan as TPS E circuit fault, this DTC also continues to return along with TPS D circuit fault and ignition relay B aswell. I have access to all the FORD & Autodata & ALLDATA wiring diagrams relating to engine management, power distribution etc but don't see any relating or common components except battery/alternator/ECU'S. The CAN-BUS layout shows connections between all affected components but have never done any work on CAN systems and wouldn't know where to start or equipment to use or what to look for. I have a good deal of experience on electrical systems  was going to try wire the engine ECU or the BCM direct to the battery or another power source thru a switch and fuse so as when the jerking occurs flick the switch and see if my voltage returns to normal and if jerking subsides and work it from there. I also have access to a C-MAX same year & engine and was tinking of changing alternator/battery for test. I believe changing the ECU or BCM requires reprogramming and security code  changing can you give me any info on this, Is the BCM module the same item as the interior fuse box and CEM/GEM modules and can these be disconnested and reconnected to check for poor connections. Regds and await your reply.

Submitted: 3 years ago.
Category: Ford
Expert:  Shantal-Mod replied 3 years ago.
I'm Shantal and I'm a moderator for this topic.
I've been working hard to find a Professional to assist you with your question, but sometimes finding the right Professional can take a little longer than expected.
I was checking to see if you had already found your answer or if you still need assistance from one of the Professionals.
Please let me know if you wish to continue waiting or if you would like for us to close your question?
Thank you,
Customer: replied 3 years ago.

Still require help please.

Expert:  Shantal-Mod replied 3 years ago.
Thank you for getting back to me. We have Professionals online all the time, unfortunately they may not have the experience needed to assist you. We will continue to look for a Professional to assist you.
However, should you wish to close your question and reverse your charges at any time please let me know.
Thank you for your patience,
Customer: replied 3 years ago.

My Problem has been resolved and do not require any assistance. Will i still be invoiced or billed as i did not receive any reply's or help from JUST ANSWERS.

Customer: replied 3 years ago.

Hi There, I have just been checking my bank details and was shocked and alarmed to find i have been billed €38 from your company approx 5 times since December 2014. I remember cancelling my account and you confirming the cancellation as i did not receive an answer to my posted question and did receive a email from you saying my account would be refunded the first €38 as i had not received any help on the question posted. CAN YOU PLEASE RECTIFY THIS AND REFUND THE FUNDS THAT HAVE BEEN DEDUCTED AND CEASE FROM TAKING ANY FURTHER FUNDS FROM MY ACCOUNT FOR A SERVICE I AM NOT USING .

Regards Kieran